Apparatuses and methods for cooling sensor components in hot formations

ABSTRACT

A downhole tool, comprising a housing; a sensor having components within the housing, the sensor being for monitoring a characteristic of a well; and one or more coolant supply lines extending to the components. A method comprising: monitoring a characteristic of a well using a sensor having components within a housing; and supplying coolant through one or more supply lines to the components. The methods and apparatuses may be used to drill steam assisted gravity drainage (SAGD) wells.

TECHNICAL FIELD

This document relates to systems and methods for cooling position sensor components while drilling gravity drainage wells in hot formations.

BACKGROUND

Wells used in heat assisted gravity drainage (HAGD) operations must be carefully positioned relative to one another to maximize production. For example, steam assisted gravity drainage (SAGD) operations generally use pairs of parallel horizontal wells (well pairs) aligned with 4-6 meters of vertical separation across kilometers of well length.

Position sensors such as magnetometers are used during drilling to ensure proper positioning of the second well relative to the first well. Many replacement position sensors may be required when drilling in a hot formation, such as a formation previously heated by a steam assisted gravity drainage (SAGD) operation, because the position sensors have a limited lifespan at such temperatures. Water may be injected into the formation to cool the formation and sensors to alleviate the number of replacement sensors used to drill or to reduce the temperature of the sensors until they are operating within their temperature specifications.

Hot formations are also known to damage downhole wireline sensors, increasing the cost of a logging operation and well operation in general. In some cases, sensors may be partially protected by a heat shield, but eventually a hot formation will lead to sensor failure. Some sensors are cooled by filling the wellbore with coolant. Other operations are carried out using a plurality of sensors, such that once a sensor fails, a new sensor is inserted and continues the operation until completion.

SUMMARY

A downhole tool, comprising a housing; a sensor having components within the housing, the sensor being for monitoring a characteristic of a well; and one or more coolant supply lines extending to the components. One or more coolant return lines may extend to the components.

A downhole tool is also disclosed comprising a housing enclosing at least a part of a sensor; one or more coolant supply lines extending to the housing; one or more coolant return lines extending to the housing; one or more first channels, formed in the housing and connected to one of one or more coolant supply lines or one or more coolant return lines, for bypassing coolant past the at least a part of the sensor; and one or more second channels, formed in the housing and connected between the one or more first channels and the other of the one or more coolant supply lines and the one or more coolant return lines in the housing, for conveying the coolant to pass over the at least a part of the sensor; in which the one or more coolant supply lines and the one or more coolant return lines are positioned within coiled tubing.

A downhole tool is also disclosed comprising a housing having a coiled tubing connector and defining a chamber terminating in an uphole direction by a ported plate; a sensor having components within the chamber, the sensor being for monitoring a characteristic of a well; and one or more coolant supply lines connected to the chamber.

A downhole tool is also disclosed comprising a housing having a coiled tubing connector, and a chamber defined by a downhole ported plate and an uphole ported plate in the housing; a sensor having components within the chamber, the sensor being for monitoring a characteristic of a well; one or more coolant supply lines extending between a coolant supply and one of the downhole ported plate or the uphole ported plate; one or more coolant return lines extending between a coolant return and the other of the downhole ported plate or the uphole ported plate.

A downhole tool is also disclosed in a downhole environment that has a higher temperature than a maximum operating temperature of the downhole tool, the downhole tool comprising a housing having a chamber defined by a downhole ported plate and an uphole ported plate in the housing; a sensor having components within the chamber, the sensor being for monitoring a characteristic of a well; one or more coolant supply lines extending to one of the downhole ported plate or the uphole ported plate; one or more coolant return lines extending to the other of the downhole ported plate or the uphole ported plate.

A downhole tool is also disclosed, comprising a housing defining a chamber terminated in an uphole direction by a ported plate; a sensor having components within the housing, the sensor being for monitoring a characteristic of a well; coil in coil tubing connected to the chamber and having one or more inner coolant supply line coils and an outer coolant return annulus.

A downhole tool is also disclosed, comprising a housing having a chamber defined by a downhole ported plate and an uphole ported plate in the housing; a sensor having components within the housing, the sensor being for monitoring a characteristic of a well; coil in coil tubing having one or more inner coolant supply line coils, connected to one of the downhole ported plate and the uphole ported plate, and an outer coolant return annulus connected to the other of the downhole ported plate and the uphole ported plate.

A downhole tool is also disclosed comprising a housing having a chamber defined by a downhole ported plate and an uphole ported plate in the housing; a sensor having components within the chamber, the sensor being for monitoring a characteristic of a well; one or more coolant supply lines extending to one of the downhole ported plate or the uphole ported plate; one or more coolant return lines extending to the other of the downhole ported plate or the uphole ported plate; in which the one or more coolant supply lines and the one or more coolant return lines are positioned within coiled tubing.

A downhole tool is also disclosed comprising a housing having a chamber defined by a downhole ported plate and an uphole ported plate in the housing; a sensor having components within the chamber; and one or more coolant supply lines extending between a coolant supply, located above ground in use, and one of the downhole ported plate or the uphole ported plate.

A downhole tool is also disclosed comprising a housing; a sensor having components within the housing, the sensor being for monitoring a characteristic of a well; one or more coolant supply lines to the components; and one or more coolant return lines to the components; in which the one or more coolant supply lines and the one or more coolant return lines comprise coil in coil tubing; and a coolant loop connected to a downhole supply portion of at least one of the one or more coolant supply lines and to a downhole return portion of at least one of the one or more coolant return lines, in which the coolant loop, downhole supply portion, and downhole return portion are enclosed within the downhole tool.

A downhole tool is also disclosed comprising a housing having a chamber defined by a downhole ported plate and an uphole ported plate in the housing; a sensor having components within the chamber, the sensor being for monitoring a characteristic of a well; one or more coolant supply lines to one of the downhole ported plate and the uphole ported plate; in which the one or more coolant supply lines comprise coil in coil tubing.

A downhole tool is also disclosed comprising: a housing having a chamber terminated in an uphole direction by a ported plate; a sensor having components within the chamber, the sensor being for monitoring a characteristic of a well; one or more coolant supply lines to the chamber; in which the one or more coolant supply lines comprise coil in coil tubing.

A downhole tool is also disclosed comprising a housing having a chamber defined in part by a ported plate; a sensor having components within the chamber, the sensor being for monitoring a characteristic of a well; one or more coolant supply lines extending to the chamber; one or more coolant return lines extending to the chamber; in which the one or more coolant supply lines and the one or more coolant return lines are positioned within coiled tubing.

A downhole tool is also disclosed comprising a housing defining a chamber terminated in an uphole direction by a ported plate and having one or more chamber bypass channels; a sensor having components within the chamber, the sensor being for monitoring a characteristic of a well; one or more coolant supply lines extending to one of the ported plate or the one or more chamber bypass channels; one or more coolant return lines extending to the other of the ported plate or the one or more chamber bypass channels.

A downhole tool is also disclosed comprising a housing defining a chamber terminated by a ported plate; a sensor having components within the chamber, the sensor being for monitoring a characteristic of a well; and one or more coolant supply lines extending between a coolant supply, located above ground in use, and the ported plate; in which the chamber has one or more ports to an exterior of the downhole tool.

A downhole tool is also disclosed comprising a housing enclosing at least a part of a sensor; one or more first channels, formed in the housing and connected to one or more supply ports in the housing, for bypassing coolant past the at least a part of the sensor; and one or more second channels, formed in the housing and connected between the one or more first channels and one or more return ports in the housing, for conveying the coolant to pass over the at least a part of the sensor.

A downhole tool is also disclosed, comprising a housing defining a chamber that has a downhole portion and an uphole portion; a sensor having components within the chamber, the sensor being for monitoring a characteristic of a well; one or more coolant supply lines extending between a coolant supply and one or more ports in one of the downhole portion or the uphole portion of the chamber; one or more coolant return lines extending between a coolant return and one or more ports in the other of the uphole portion or the downhole portion of the chamber.

A downhole tool, for example within a previously drilled well, is also disclosed, the downhole tool comprising a housing; a sensor having components within the housing; one or more coolant supply lines extending between a coolant supply, located above ground in use, and the components; one or more coolant return lines extending between the components and a coolant return located above ground in use; and in which the one or more coolant supply lines and the one or more coolant return lines are positioned within coiled tubing.

A downhole tool within a previously drilled well is also disclosed, comprising a housing; a sensor having components within the housing, the sensor being for monitoring a characteristic of a well; one or more coolant supply lines extending to the components; and one or more coolant return lines extending to the components; in which the one or more coolant supply lines and the one or more coolant return lines comprise coil in coil tubing.

A downhole tool is also disclosed, comprising a housing; a sensor having components within the housing, the sensor being for monitoring a characteristic of a well; one or more coolant supply lines extending between a coolant supply and the components; one or more coolant return lines extending between the components and a coolant return; and coil in coil tubing, in which the one or more coolant supply lines and the one or more coolant return lines are positioned within the coiled tubing.

A downhole tool is also disclosed, comprising a housing; a sensor having components within the housing, the sensor being for monitoring a characteristic of a well; one or more coolant supply lines extending between a coolant supply, located above ground in use, and the components; one or more coolant return lines extending between the components and a coolant return located above ground in use; the one or more coolant supply lines and the one or more coolant return lines each comprising coiled tubing; and a coolant loop connected to a downhole supply portion of at least one of the one or more coolant supply lines and to a downhole return portion of at least one of the one or more coolant return lines, in which the coolant loop, downhole supply portion, and downhole return portion are enclosed within the downhole tool.

A downhole tool is also disclosed, comprising a housing; a logging sensor having components within the housing, the sensor being for monitoring a characteristic of a well, the logging sensor being one or more of a bond log sensor, a resurveying logging sensor, gamma ray logging sensor, a spontaneous potential logging sensor, a resistivity logging sensor, a density logging sensor, a sonic logging sensor, a caliper logging sensor, a video camera, and a nuclear magnetic resonance logging sensor; one or more coolant supply lines extending to the components; one or more coolant return lines extending to the components; the one or more coolant supply lines and the one or more coolant return lines each comprising coiled tubing; and a coolant loop connected to a downhole supply portion of at least one of the one or more coolant supply lines and to a downhole return portion of at least one of the one or more coolant return lines, in which the coolant loop, downhole supply portion, and downhole return portion are enclosed within the downhole tool.

A downhole tool is also disclosed, comprising a housing; a sensor having components within the housing, the sensor being for monitoring a characteristic of a well; one or more coolant supply lines extending to the components; one or more coolant return lines extending to the components; a coolant loop connected to a downhole supply portion of at least one of the one or more coolant supply lines and to a downhole return portion of at least one of the one or more coolant return lines, in which the coolant loop, downhole supply portion, and downhole return portion are enclosed within the downhole tool; and one or more channels formed in the housing for bypassing coolant past the components and conveying the coolant to pass over the components.

A position sensor is also disclosed comprising a housing; a sensor having components within the housing, the sensor being for monitoring in use the location of a second well during drilling of the second well while the housing is in a first well; one or more coolant supply lines extending to the components; and one or more coolant return lines extending to the components.

A method is also disclosed comprising monitoring a characteristic of a well using a sensor having components within a housing; and supplying coolant through one or more supply lines from a coolant supply to the components. The method may include returning coolant through one or more return lines from the components to a coolant return.

A method is also disclosed comprising monitoring a characteristic of a well using a sensor having components within a chamber defined by an uphole ported plate and a downhole ported plate in a housing; supplying coolant through one or more supply lines to one of the uphole ported plate or downhole ported plate to bypass the components and convey the coolant to pass over the components; and returning coolant from the other of the uphole ported plate or the downhole ported plate to one or more return lines.

A method is also disclosed comprising monitoring a characteristic of a well using a sensor having components within a chamber bounded in an uphole direction by a ported plate; supplying coolant through one or more supply lines to the chamber to bypass the components and convey the coolant to pass over the components; and returning coolant from the chamber to one or more return lines.

A method is also disclosed comprising monitoring a characteristic of a well using a sensor having components within a chamber bounded in an uphole direction by a ported plate; supplying coolant through coiled tubing to the chamber; and returning coolant from the chamber to one or more coolant return lines.

A method is also disclosed comprising monitoring a characteristic of a well using a sensor having components within a chamber defined by an uphole ported plate and a downhole ported plate in a housing; supplying coolant through one or more supply lines to one of the uphole ported plate or the downhole ported plate; and returning coolant from the other of the uphole ported plate and the downhole ported plate to one or more return lines; in which the well has a higher temperature than a maximum operating temperature of the sensor.

A method is also disclosed comprising monitoring a characteristic of a well using a sensor having components within a chamber defined by an uphole ported plate and a downhole ported plate in a housing; supplying coolant through one or more coolant supply lines to one of the uphole ported plate and the downhole ported plate; and returning coolant from the other of the uphole ported plate and the downhole ported plate to one or more coolant return lines; in which the one or more coolant supply lines and one more coolant return lines comprise coiled tubing.

A method is also disclosed comprising monitoring a characteristic of a well using a sensor having components within a chamber bounded in an uphole direction by a ported plate; supplying coolant through one or more inner coils of coil in coil tubing to the chamber; and returning coolant from the chamber to an outer annulus of the coil in coil tubing.

A method is also disclosed comprising monitoring a characteristic of a well using a sensor having components within a chamber defined by an uphole ported plate and a downhole ported plate in a housing; supplying coolant through one or more inner coils of coil in coil tubing to one of the uphole ported plate and the downhole ported plate; and returning coolant from the other of the uphole ported plate and the downhole ported plate to an outer annulus of the coil in coil tubing.

A method is also disclosed comprising monitoring a characteristic of a well using a sensor having components within a housing; supplying coolant through one or more supply lines positioned within coiled tubing to the chamber to bypass the components and convey the coolant to pass over the components; and returning coolant from the chamber to one or more return lines positioned within the coiled tubing.

A method is also disclosed comprising monitoring a characteristic of a well using a sensor having components within a chamber defined by an uphole ported plate and a downhole ported plate in a housing; supplying coolant through one or more coolant supply lines from a coolant supply located above ground to one of the uphole ported plate and the downhole ported plate; and returning coolant through one or more coolant return lines from the other of the uphole ported plate and the downhole ported plate to a coolant return located above ground.

A method is also disclosed comprising monitoring a characteristic of a well using a sensor having components within a housing; supplying coolant through one or more coolant supply lines, positioned within coiled tubing, from a coolant supply located above ground to the components; and returning coolant through one or more coolant return lines, positioned within the coiled tubing, from the components to a coolant return located above ground.

A method is also disclosed comprising monitoring a characteristic of a well using a sensor having components within a housing; supplying coolant through one or more coolant supply lines, positioned within coil in coil tubing, from a coolant supply to the components; and returning coolant through one or more coolant return lines, positioned within the coil in coil tubing, from the components to a coolant return.

A method is also disclosed comprising monitoring a characteristic of a well using a sensor having components within a chamber defined by an uphole ported plate and a downhole ported plate in a housing; supplying coolant through one or more coolant supply lines from a coolant supply to one of the uphole ported plate and the downhole ported plate; and returning coolant through one or more coolant return lines from the other of the uphole ported plate and the downhole ported plate to a coolant return; in which the one or more coolant supply lines and the one or more coolant return lines comprise coil in coil tubing.

A method is also disclosed comprising monitoring a characteristic of a well using a sensor having components within a chamber defined by an uphole ported plate and a downhole ported plate in a housing; supplying coolant through one or more coolant supply lines, positioned within coiled tubing, to one of the uphole ported plate and the downhole ported plate; and returning coolant through one or more coolant return lines, positioned within coiled tubing, from the other of the uphole ported plate and the downhole ported plate.

A method is also disclosed comprising monitoring a characteristic of a well using a sensor having components within a chamber bounded in an uphole direction by a ported plate; supplying coolant through one or more coolant supply lines to the chamber; and returning coolant through one or more coolant return lines from the chamber; in which the one or more coolant supply lines and the one or more coolant return lines comprise coil in coil tubing.

A method is also disclosed comprising monitoring a characteristic of a well using a sensor having components within a chamber bounded in an uphole direction by a ported plate; supplying coolant through one or more coolant supply lines, positioned within coiled tubing, to the chamber; and returning coolant through one or more coolant return lines, positioned within coiled tubing, from the chamber.

A method is also disclosed comprising monitoring a characteristic of a well used for heat assisted gravity drainage using a sensor having components within a housing; and supplying coolant through one or more supply lines from a coolant supply to the components; and returning coolant through one or more return lines from the components to a coolant return.

A method is also disclosed comprising monitoring a characteristic of a well using a sensor having components within a housing connected to a tubing string; and switching between a first mode and a second mode; in which the first mode comprises supplying coolant to the components through one or more supply lines to the components, and returning coolant through one or more return lines from the components; in which in the second mode coolant is supplied to the components through the one or more supply lines and the one or more return lines and returned up the tubing string.

A method is also disclosed comprising monitoring a characteristic of a well using a sensor having components within a housing; and supplying coolant through one or more supply lines from a coolant supply to bypass the components; supplying the coolant to pass over the components; and returning coolant through one or more return lines from the components to a coolant return.

A method is also disclosed comprising monitoring a characteristic of a well using a sensor having components within a coolant loop within a downhole tool; and supplying coolant to the coolant loop through a downhole supply portion of one or more supply lines; and returning coolant from the coolant loop through a downhole return portion of one or more return lines; in which the coolant loop, downhole supply portion, and downhole return portion are enclosed within the downhole tool; in which the one or more coolant supply lines and the one or more coolant return lines comprise coil in coil tubing.

A method is also disclosed comprising monitoring a characteristic of a well using a sensor having components within a coolant loop within a downhole tool; and supplying coolant through one or more supply lines from a coolant supply to bypass the components and convey the coolant to pass over the components; and returning coolant from the coolant loop through a downhole return portion of one or more return lines; in which the coolant loop, downhole supply portion, and downhole return portion are enclosed within the downhole tool.

A method is also disclosed comprising monitoring a characteristic of a well using a sensor having components within a coolant loop within a downhole tool; and supplying coolant from a coolant supply located above ground to the coolant loop through a downhole supply portion of one or more supply lines; and returning coolant from the coolant loop through a downhole return portion of one or more return lines to a coolant return located above ground; in which the coolant loop, downhole supply portion, and downhole return portion are enclosed within the downhole tool; in which the one or more coolant supply lines and the one or more coolant return lines comprise coiled tubing.

A method is also disclosed comprising monitoring a characteristic of a previously drilled well using a sensor having components within a housing; and supplying coolant through one or more supply lines to the components; and returning coolant through one or more return lines from the components; in which the one or more coolant supply lines and the one or more coolant return lines comprise coil in coil tubing.

A method of drilling a second well in a formation that contains a first well and has been heated by a heat assisted gravity drainage operation, the method comprising monitoring the location of the second well using a position sensor having components in the first well; drilling the second well using signals from the position sensor; supplying coolant through one or more supply lines from a ground surface to the components; and returning coolant through one or more return lines from the components to the ground surface; in which one of the first well and the second well is a heat injection well and the other of the first well and the second well is a production well.

A method is also disclosed of drilling a second well in a formation that contains a first well and has been heated by a heat assisted gravity drainage operation, the method comprising monitoring the location of the second well using a position sensor having components in the first well; drilling the second well using signals from the position sensor; and cooling the components by supplying coolant through one or more supply lines from a ground surface to the components and returning coolant through one or more return lines from the components to the ground surface; in which one of the first well and the second well is a heat injection well and the other of the first well and the second well is a production well.

A position sensor is also disclosed comprising a housing, for example made of one or both of ferrous or non ferrous material; a sensor having components within the housing, the sensor being for monitoring the location of a second well while drilling of the second well while the housing is in a first well; one or more coolant supply lines extending between a coolant supply and the components; and one or more coolant return lines extending between the components and a coolant return.

A method is also disclosed comprising monitoring a characteristic of a well using a sensor having components within a chamber bounded by a ported plate; supplying coolant through one or more coolant supply lines to the chamber; and discharging coolant through one or more ports in the chamber to an exterior of the downhole tool.

A method is also disclosed comprising monitoring a characteristic of a well using a sensor having components within a housing; supplying coolant through one or more coolant supply lines to the housing from a coolant supply located above ground; and discharging coolant through one or more ports in the housing for return up the wellbore.

A downhole tool is also disclosed comprising a housing; a sensor having components within the housing, the sensor being for monitoring a characteristic of a well; and one or more coolant supply lines extending between a coolant supply, located above ground in use, and the chamber; in which the one or more coolant supply lines comprise coiled tubing connected to the housing.

A downhole tool and method of use is also disclosed comprising a housing enclosing at least a part of a tool component; one or more coolant return lines at least a portion of which is extended to the housing; and one or more coolant supply lines including at least a first portion and a second portion, the first portion being extended to the housing, the second portion being extended, at a point uphole of the housing, to the one or more coolant return lines.

A downhole tool and method of use is also disclosed, comprising a tool component such as a production pump; one or more coolant supply lines extending to the production pump; and one or more coolant return lines extending from the production pump. All embodiments in this disclosure that include sensors may be adapted to incorporate a tool component in place or in addition to the sensor.

In various embodiments, there may be included any one or more of the following features: The one or more coolant supply lines extend to a coolant supply. One or more coolant return lines extend to the components. The one or more coolant return lines extend to a coolant return. The chamber terminates or is bound in an uphole direction by a ported plate. The one or more coolant supply lines extend between a coolant supply and one of the downhole ported plate or the uphole ported plate. The one or more coolant return lines extend between a coolant return and the other of the downhole ported plate or the uphole ported plate. The chamber has one or more ports to an exterior of the downhole tool. The housing has a coiled tubing connector. The chamber has one or more chamber bypass channels. The well has a higher temperature than the maximum operating temperature of the downhole tool. The components of the position sensor are contained within coiled tubing. The coiled tubing is coil in coil tubing. The one or more supply lines are defined by one or more inner coils of the coil in coil tubing, and the one or more return lines are defined by one or more inner coils of the coil in coil tubing. The one or more supply lines are defined by one or more inner coils of the coil in coil tubing, and the one or more return lines are defined by an outer annulus of the coil in coil tubing. The first well and the second well are a parallel well pair. The first well and the second well are an intersecting well pair. Drilling the second well further comprises advancing the components towards a toe end of the first well. The first well and the second well are horizontal wells. The position sensor comprises a magnetometer. The components comprise the magnetometer. Carrying out a heat assisted gravity drainage operation, such as a SAGD operation, using the first well and the second well. The components are within a chamber defined by the housing and connected to receive coolant from the one or more coolant supply lines through one or more ports in a downhole end of the chamber. The downhole end and an uphole end of the chamber are each defined by a respective ported plate mounted within the housing. The components are mounted to one or both of the ported plate that defines the downhole end of the chamber and the ported plate that defines the uphole end of the chamber. The components are located within coiled tubing, for example fixed to the end of the coiled tubing, in one of a pair of horizontal wells used for heat assisted gravity drainage. The one or more coolant supply lines and the one or more coolant return lines comprise coiled tubing. The coiled tubing comprises coil in coil tubing. The one or more coolant supply lines comprise one or more inner coils of the coil in coil tubing. The one or more coolant return lines comprise an outer annulus of the coil in coil tubing. The one or more coolant return lines comprise one or more inner coils of the coil in coil tubing. The one or more coolant supply lines are positioned within the coiled tubing. The one or more coolant return lines are positioned within the coiled tubing. A coolant loop is connected to a downhole supply portion of at least one of the one or more coolant supply lines and to a downhole return portion of at least one of the one or more coolant return lines, in which the coolant loop, downhole supply portion, and downhole return portion are enclosed within the downhole tool. The coolant supply is located above ground in use. The coolant return is located above ground in use. The components are within a chamber in the housing, the chamber having a downhole portion and an uphole portion. The one or more coolant supply lines are connected to supply fluid through one or more ports in the downhole portion of the chamber. The one or more coolant return lines are connected to return fluid through one or more ports in the uphole portion of the chamber. The downhole portion and the uphole portion of the chamber are each defined by respective ported plates mounted within the housing. The components are mounted to one or both of the ported plate that defines the downhole portion of the chamber and the ported plate that defines the uphole portion of the chamber. The housing is in one of a pair of horizontal wells used for heat assisted gravity drainage. The sensor is a position sensor. The position sensor is for monitoring the location of a second well during drilling of the second well while the housing is in a first well. The downhole tool is positioned within a previously drilled well. The sensor is a logging sensor. The logging sensor comprises one or more of a bond log sensor, a resurveying logging sensor, gamma ray logging sensor, a spontaneous potential logging sensor, a resistivity logging sensor, a density logging sensor, a sonic logging sensor, a caliper logging sensor, a video camera, and a nuclear magnetic resonance logging sensor. Channels are formed in the housing for bypassing coolant past the components and conveying the coolant to pass over the components; and a coiled tubing connector is in the housing, the coiled tubing connector having ports communicating with the channels to provide coolant supply and coolant return. The channels comprise: one or more first channels, formed in the housing and connected to one or more supply ports in the housing, for bypassing coolant past the at least a part of the sensor; and one or more second channels, formed in the housing and connected between the one or more first channels and one or more return ports in the housing, for conveying the coolant to pass over the at least a part of the sensor. The housing comprises a coiled tubing connector having ports communicating with the one or more first channels and the one or more second channels to provide coolant supply and coolant return. The downhole portion and the uphole portion of the chamber are each defined by a respective ported plate mounted within the housing. The components are within a chamber defined by the housing and connected to receive coolant from the one or more coolant supply lines through one or more ports in a downhole portion of the chamber. The downhole portion and an uphole portion of the chamber are each defined by a respective ported plate mounted within the housing. The components are mounted to one or both of the ported plate that defines the downhole portion of the chamber and the ported plate that defines the uphole portion of the chamber. Monitoring the location of the second well comprises monitoring the location of a drill string. Switching between: a first mode where coolant is supplied through the one or more supply lines and returned through the one or more return lines; and a second mode where coolant is supplied through the one or more supply lines and the one or more return lines and returned up the coiled tubing. The coolant is returned up the annulus of the coiled tubing in the second mode. The housing is part of a downhole tool, and further comprising a coolant loop connected to a downhole supply portion of at least one of the one or more coolant supply lines and to a downhole return portion of at least one of the one or more coolant return lines, in which the coolant loop, downhole supply portion, and downhole return portion are enclosed within the downhole tool. Drilling a second well, in which monitoring further comprises monitoring the location of the second well during drilling of the second well while the housing is in a first well. The components are positioned within a previously drilled well. Monitoring further comprises logging. Supplying comprises bypassing coolant past the components and conveying the coolant to pass over the components. Coolant bypasses the components before being conveyed to pass over the components. The one or more supply lines are defined by one or more inner coils of the coil in coil tubing, and the one or more return lines are defined by one or more inner coils of the coil in coil tubing. The one or more supply lines are defined by one or more inner coils of the coil in coil tubing, and the one or more return lines are defined by an outer annulus of the coil in coil tubing. A temperature sensor is connected to control fluid flow through the one or more coolant supply lines based on a temperature sensed by the temperature sensor. The temperature sensor comprises a thermostat valve. The temperature sensor is at least partially within the housing. The thermostat valve is connected to open between the housing and the well bore at sensed temperatures above a predetermined temperature.

These and other aspects of the device and method are set out in the claims, which are incorporated here by reference.

BRIEF DESCRIPTION OF THE FIGURES

Embodiments will now be described with reference to the figures, which are not to scale, in which like reference characters denote like elements, by way of example, and in which:

FIG. 1 is a side elevation view, partially in section, of a coil in coil tubing rig being used to supply and return coolant to a position sensor in a production well while an injector well is being drilled.

FIG. 2 is a side elevation view, partially in section, of a position sensor contained in a housing with a sensor chamber, and with arrows illustrating coolant fluid movement through the housing.

FIG. 3 is a side elevation section view of a position sensor that has two coolant supply lines.

FIG. 4 is a section view taken along the 4-4 section lines from FIG. 3.

FIG. 5 is a side elevation section view of a position sensor that has one coolant supply line.

FIGS. 6 and 7 are side elevation views illustrating uphole and downhole port assemblies, respectively, for use with the position sensors of FIGS. 8 and 9.

FIG. 8 is a side elevation section view of another embodiment of a position sensor that has a single coolant supply line.

FIG. 9 is a side elevation section view of another embodiment of a position sensor that has a plurality of coolant supply lines.

FIG. 10 is a section view taken along the 10-10 section lines from FIGS. 6 and 7.

FIG. 11 is a section view taken along the 11-11 section lines from FIGS. 6 and 7.

FIG. 12 is an exploded view of the embodiment of FIG. 3 with the supply and return lines removed for clarity.

FIGS. 13-18 are section views taken along the 13-13, 14-14, 15-15, 16-16, 17-17, and 18-18 section lines, respectively, shown in FIG. 12.

FIG. 19 is a perspective view of an exemplary valve and line arrangement for switching modes as described below.

FIGS. 20A-C are a side perspective view, partially in section (FIG. 20A), a section view taken along the 20B-20B section lines of FIG. 20A (FIG. 20B), and a top plan view, partially in section (FIG. 20C), of an embodiment of the apparatus housing a sonic tool.

FIG. 21 is a side elevation view of an embodiment of a downhole caliper tool.

FIG. 22 is a side elevation view of an embodiment of a downhole resistivity tool.

FIG. 23 is a side elevation view, partially in section, of a downhole video camera tool.

FIG. 24 is a side elevation view, partially in section, of a downhole tool that supplies a portion of the coolant to the housing and a portion to the return lines.

DETAILED DESCRIPTION

Immaterial modifications may be made to the embodiments described here without departing from what is covered by the claims.

Steam-assisted gravity drainage (SAGD) is a hydrocarbon-producing process that is used to extract viscous hydrocarbons from hydrocarbon-producing reservoirs located under the ground surface. Conventional methods of hydrocarbon extraction, such as mining and/or drilling are generally ineffective or inefficient at extracting viscous hydrocarbons such as bitumen, crude oil, or heavy oil, and thus SAGD and other heat-assisted gravity drainage (HAGD) methods are used to add heat to the hydrocarbons to lower their viscosity to a point where they may be collected in a well for production. Examples of the type of hydrocarbon-producing reservoirs that contain these viscous hydrocarbons include oil sands located primarily in Canada and Venezuela.

The injection and production wells may be horizontally drilled wells that extend distances of several kilometers from heel-to-toe. Steam is injected into the reservoir along at least a portion of the length of the injection well, permeating the formation and forming a steam chamber throughout the reservoir around the injection well. In some cases other suitable species may be injected other than or in addition to steam, including heated solvent in the case of vapor extraction (VAPEX) or air in the case of toe heel air injection (THAI). Viscous hydrocarbons contained within the steam chamber are heated and reduce in viscosity enough to drain by gravity into the production well, where they are pumped to the surface. This process allows viscous hydrocarbons contained within large, relatively horizontal reservoirs under the ground surface to be effectively extracted.

FIG. 1 illustrates a horizontal well pair used for steam assisted gravity drainage (SAGD) operations. In some cases the methods disclosed herein may be carried out intersecting wells. The well pair comprises a production well 10 and an injection well 12 above the production well 10. There are no requirements as to which of wells 10 and 12 should be drilled first, but in the example shown the lower production well 10 is drilled first. In some cases the wells 10 and 12 may be drilled simultaneously although one of the wells may be concurrently drilled ahead of the other.

SAGD wells may be shallow, and a slant rig (not shown) may be employed to drill the wells a few hundred meters deep. With a slant rig, the drill pipe enters the ground at an angle of about 45° angle, so that the well can build quickly to 90°, i.e. horizontal. After being drilled in the desired zone, the first well 14, in this case production well 10, may be cased, for example with slotted or perforated liner (not shown) for stability. In other cases, SAGD wells may be drilled from a vertical well.

Once the user is ready to drill the second well 16, in this case injection well 12, a wireless or wireline tool such as position sensor 18 described below may be deployed inside the tubing of first well 14. Such a tool is used because the relative distance between the injector and production wells may affect potential recovery. The wells should be located sufficiently near to one another such that heavy oil heated at the injector well may drain into the production well. If the wells are located too near to one another, steam or air from the injector well may shunt into the production well, and if the wells are located too far from one another, the heated heavy oil may not extend to the production well.

The wireline tool determines the location of second well 16 relative to first well 14. This information is then used to steer the second well 16 parallel or within sufficient proximity to first well 14. The bottom hole assembly 20 in second well 16 may include a steering mechanism (not shown), such as a steerable motor with bent sub or a rotary steerable system, for steering a drill bit 22. Position sensor 18 may use measurement while drilling technology such as magnetic ranging or nuclear ranging. There are several magnetic ranging techniques that may be used, including active and passive ranging.

Active techniques generally involve the production of a magnetic field in the first well 14 or second well 16, followed by detection in the other of wells 14 or 16 by a sensor such as a magnetometer. For example, the tool 18 may contain a solenoid (not shown) that produces a magnetic field, with known strength and field pattern, that is then detected by a sensor (not shown) in the second well 16. The tubing and slotted casing may affect the magnetic field but these effects can be removed by calibrating the solenoid inside the same size tubing and casing on the surface. The magnitude of the measured magnetic field indicates the separation of the two wells 10, 12 and the direction of the magnetic field indicates their relative positions. In another example, the second well 16 generates the magnetic field using one or more permanent magnets mounted in a near-bit sub (not shown), or on the mud motor (not shown) in some cases. The permanent magnets rotate with the drill bit 22 thus producing an oscillating magnetic field that is detected by a magnetometer in the position sensor 18 as the drill bit 22 passes by the position sensor 18. The distance between the wells 14, 16 is deduced from the variation in the magnetic field with measured depth of the drill bit. In yet another example of an active technique, a wire (not shown) is used in first well 14 to carry a current to the toe 24 of first well 14 where the wire is grounded to the casing 26. Most of the current returns to the surface through the casing 26 but a small amount of current leaks into the formation 28 at each foot along its length. The leakage current varies from foot to foot depending on the properties of the casing, the cement, and the formation resistivity. The net current produces an azimuthal magnetic field around the wellbore that can be measured with a magnetometer in the second well 16. Other sensors and sensing techniques may be used.

Passive ranging techniques are generally less effective than active techniques. For example, permanent magnets may be installed inside the steel casing and alternately magnetized N-S and S-N to create a discernable magnetic field pattern. The magnetic field is measurable within the second well 16 and the information employed to steer drill bit 22. Afterwards, the permanent magnets may be recovered from the cased well.

Once a SAGD field is up and running, the formation 28 may be pumped with heat for a suitable amount of time, such as years. Often a single formation 28 will be injected with heat from plural well pairs, in order to heat the entire formation. However, a user may desire for a variety of reasons to drill additional wells in the formation 28 after heating. For example, a user may want to re-drill an injection well to replace an existing injection well that is not properly aligned with the corresponding production well, or to replace an injection well that has been damaged. In other cases, a user may desire to place an additional well pair at a location in the formation 28 where the steam chamber has not adequately penetrated. A user may also simply wish to provide a denser matrix of well pairs in order to facilitate maximum draw from the formation 28. In some cases a wedge well may be drilled.

Components used in the position sensors described above are generally electrical components and include microprocessors, accelerometers, magnetomers, or transducers for example. A limitation on the use of such components may be the high temperatures that are often present and associated with a formation 28 made hot from the SAGD process. Downhole ambient temperatures can approach those of saturated steam and many electrical components that are commercially available cannot operate reliably with such conditions.

As a result of the temperature limitations on these tools, drilling wells in such hot formations 28 is made more difficult than conventional drilling of these wells. For example, one approach taken is to have in stock a plurality of replacement position sensors that are used one at a time in the first well 14 until inevitable failure of the sensor. Upon failure, the old sensor is withdrawn and a new sensor is inserted. This process is continued until the second well 16 is drilled. This approach is expensive because it requires the purchase of a plurality of replacement sensors, as well as the additional labor and tool rental time required to change out and calibrate each new sensor. This approach may not be possible in wells that are above a certain temperature.

Another approach is to cool off the formation 28 in the vicinity of the first well 14. This approach involves the injection into first well 14 of coolant such as water. Again, this approach is also expensive for various reasons. Firstly, it requires large amounts of water, due to the large volume of formation 28 that must be cooled, and due to other factors such as non uniform dispersal into the formation resulting in lingering hot spots that can only be cooled by continual pumping of coolant. Most or all of the injected water must then be recovered and removed from produced bitumen once operations begin again. Secondly, the injected water cools the formation, meaning that SAGD operations cannot be immediately resumed after the well 16 is drilled because the formation 28 temperature must be raised again by additional and costly steam injection. In addition, the heat plants supplying steam to the formation 28 must be shut down months in advance in order to assist this method. It generally takes months after drilling to get the temperature back up to sufficient levels. Thirdly, this approach imparts a temperature shock on the casing of the first well sufficient to strain and sometimes damage the casing, which may be difficult or impossible to repair.

Referring to FIG. 1, a method of drilling a second well 16 in a formation 28 that contains a first well 14 and has been heated by a heat assisted gravity drainage operation is illustrated. In the example shown the second well 16 is the upper injector well 12, but this orientation may be reversed and the second well 16 may be the production well 10. The location of the second well 16 is monitored using a position sensor 18 having components 30 in the first well 14. The location of the second well 16 may be indirectly monitored by monitoring the position of the drill bit 22 or the drill string.

The second well 16 is drilled using the drill bit 22 and signals from the position sensor 18. Such signals may be used in various ways in order to aid in the steering of drill bit 22. In one example, the signals are routed to a controller (not shown) that is set to automatically steer drill bit 22 in order to achieve a predetermined distance and alignment with the first well 14. In another example, the signals are sent wirelessly or by wire to a console (not shown) where a user interprets the signals or data from the signals in order to manually guide steering of the drill bit 12.

Referring to FIGS. 1 and 2, the components 30 are cooled by supplying coolant through one or more supply lines 32 from a ground surface 36 to the components 30 and returning coolant through one or more return lines 34, such as a coil annulus, from the components to the ground surface 36. FIG. 2 illustrates an exemplary position sensor 18 in greater detail than shown in FIG. 1. Position sensor 18 has a housing 54, components 30 of a sensor 56, one or more coolant supply lines 32 and one or more coolant return lines 34. Components 30 are located within housing 54 (FIG. 1), the sensor 56 being for monitoring the location of a drill bit 22 (FIG. 1) during drilling of second well 16 while the housing or flask 54 is in first well 14.

The components 30 contained within housing 54 may include a magnetometer as sensor 56. Other components 30 may be used, such as accelerometers, e-magnets, transducers, wired or wireless transmitters and receivers, and other suitable electronic components. In some cases components 30 may include a magnetic field generator (not shown) instead of a magnetometer. In this case, the position sensor 18 may incorporate other components, such as a magnetometer, that are to be located during drilling in the second well 16. In general when components are mounted in the second well 16, such components may be sufficiently cooled by drilling fluid and may not require a coolant system such as the one used in first well 14 described herein.

Referring to FIG. 2, the components 30 may be housed within a chamber 58 defined by the housing 54. Chamber 58 may be connected to receive coolant from the one or more coolant supply lines 32 through one or more ports 60 in a downhole portion, such as downhole end 62 of the chamber 58. The components 30 may be immersed in coolant in use. The downhole portion and an uphole portion, such as uphole end 64 of the chamber 58 may be each defined by ported plates 66 and 68, respectively, mounted within the housing 54. As shown, the components 30 may be mounted to one or both downhole ported plate 66 and uphole ported plate 68. Housing 54 may be designed to allow the one or more supply lines 32 to bypass components 30 in a downhole direction 72, so that coolant from the one or more supply lines 32 may then reverse direction and wash over components 30 in an uphole direction 74. Thus, the portion of components 30 that are situated furthest downhole receive the coolest of coolant supply fluid. This direction of flow may be reversed. The lines 32 and 34 may be oriented as shown to ensure that fluid is circulated through the chamber 58 in one direction only, in this case from downhole end 62 to uphole end 64. Such a circulation loop reduces the possibility of stagnant coolant being retained and overheated in chamber 58 as may occur if fluid were directly supplied to and removed from chamber 58 from the same ported plate. The supply lines 32 may supply coolant to chamber 58 by passing through one or more ports 60 of ported plate 66 into a secondary chamber 76 downhole of the chamber 58, and then reversing direction and entering the chamber 58 by passing through one or more ports 60 in the same ported plate 66 as shown. In other embodiments, ported plate 66 is a manifold that combines plural supply lines 32 and directly supplies fluid to chamber 58. A wireline 70 may be used to communicate signals between components 30 and ground surface 36 (FIG. 1).

Coiled tubing may be used with the methods and apparatuses disclosed herein. For example, the one or more supply lines and the one or more return lines may comprise coiled tubing as shown. The example in FIG. 1 illustrates a coiled tubing rig 38 used to contain and position the components 30 of the position sensor 18 within coiled tubing 40, in this case coil in coil tubing. Coiled tubing has an advantage of allowing the position sensor 18 to be precisely repositioned in an inclined well such as a directional or horizontal well without requiring additional components. Coiled tubing also allows the coolant to be enclosed within the downhole tool. For example, the injection rate of coiled tubing 40 at rig 38 may be controlled to advance the components 30 towards a toe end 24 of the first well 14 at the desired rate and temperature without dumping unwanted fluid in the well bore. By contrast, conventional wireline sensors may require additional components such as tractors or hydraulic tubing to reposition the sensors in a directional or horizontal well.

As shown in FIG. 1, coil in coil tubing 40 may be used to contain the components 30 of position sensor 18. The one or more supply lines 32 may comprise, for example be defined directly or indirectly by, one or more inner coils 42 of the coil in coil tubing. The one or more return lines 34 may comprise, for example, be defined at least in part by, an outer annulus 44 of the coil in coil tubing. One or more coolant return lines 34 may comprise, for example, be defined at least in part by, one or more inner coils 42 (FIG. 5) of the coil in coil tubing. In some cases, one or both of lines 32 and 34 are positioned within coiled tubing 40, for example if lines 32 or 34 are tubulars positioned within the coiled tubing 40. Such tubulars may be made of the same or different material as the coiled tubing. Pumping return coolant up the annulus provides a shielding effect to coolant being supplied through the supply lines 32, because the return coolant insulates the supply coolant from heat from the formation 28. This effect will be realized to some extent with the use of a return line 34 in general. In the example shown, a pump 46 may be used to pump coolant from a coolant supply such as a reservoir 48, down supply line 32 to components 30, up return line 34, and into a coolant return such as a reservoir 52 at ground surface 36. A pump (not shown) may also be used on the return line 34. In some embodiments, the one or more supply lines 32 are defined by one or more inner coils of the coil in coil tubing, and the one or more return lines 34 are defined by one or more inner coils of the coil in coil tubing. Reservoirs 48 and 52 may be independent, linked, or may be the same reservoir in some cases. A cooling system (not shown) may be used to cool reservoir fluid. In some cases the heated coolant may be used to heat a device or structure such as a building above ground. Coolant may be recycled by these or other methods. Although coil in coil tubing is illustrated by concentric coil in coil tubing, other coil in coil tubing may be used, such as coil in coil tubing with plural inner tubes.

Referring to FIGS. 3-5 embodiments of a position sensor 18 are illustrated that have a single supply line 32 (FIG. 5) or plural supply lines 32 (FIG. 3). Supply and return lines 32 and 34, respectively, may run along the entire length of the coiled tubing. Other numbers of lines 32 or 34 may be used. In both FIGS. 3 and 5, each supply line 32 passes through a series of ported plates 78 en route to secondary chamber 76 at the end of the sensor 18. Each line 32 may be secured within a port 60 in the ported plates 78 by a suitable mechanism such as one or more set screws 80. Gaskets (not shown) such as O-rings may be used to seal the space between each plate 78 and each line 32. In the multi supply example of FIGS. 3 and 4, two supply lines 32 provide coolant to chamber 76, which then supplies coolant to sensor chamber 58 through two open ports 61 in the two most downhole plates 79. Coolant is then returned from chamber 58 up the annulus 44 and around supply lines 32 within coiled tubing 40. In the single supply example of FIG. 5, supply line 32 supplies coolant to chamber 76 through the most downhole plate 81 shown, which then supplies coolant to chamber 58 through ports 63 in the two most downhole plate 81 and 83. Coolant leaves chamber 58 through return line 34, which connects to chamber 58 through another port 65 in the plate 85 that defines the uphole end 81 of chamber 58 as shown. Plate 87 is the most uphole plate in the system shown.

FIGS. 6-11 show various parts that make up the chamber 58 in another embodiment of a position sensor 18 housing 54. FIGS. 6 and 7 illustrate the uphole and downhole ported plate assemblies 82, 84, respectively. The uphole manifold 82 may have a pin 90 and the downhole assembly 84 may have a box 92 for mounting the components 30 (not shown) within chamber 58 (not shown) when the tool is assembled. Pin 90 and box 92 may be part of a tubular 91 provided for housing one or more wirelines 70 (shown in FIG. 2) for operating sensors 18 or 19. FIGS. 10 and 11 illustrate the two types of ported plates 86 and 88 used in both assemblies 82, 84. FIGS. 8 and 9 illustrate the assemblies 82 and 84 connected to give a single supply embodiment (FIG. 8) and a plural supply embodiment (FIG. 9).

A test was carried out using a housing 54 at the end of two 1900 meters of coiled one way coolant line within a steam truck. Thus, there was no return line washing over the coil as would be present in the examples shown in the drawings. The removal of the return line represents a worst case scenario, i.e. if the return line 34 failed in a real life application of using the tool. Steam was injected into the apparatus until all the components reached a temperature above 240° C. The temperature was held at 240° C. for two hours before coolant was pumped into both coils at a combined flow rate of 19 liters/minute (0.019 cubic meters/min) and 1145 psi. The temperature of the tool dropped below the target temperature of 120° C. Note that the flow rate can be brought up substantially by adding additional coolant. In a downhole environment the returning fluid would add an additional barrier insulating the injection fluid from the formation temperature. This test illustrated that the sensors could be adequately cooled using a fraction of the amount of water used previously to cool down the formation, even if the coolant did not return to the surface.

A well pair may originate from two separate mother wells, or from a single multilateral mother well to reduce environmental impact. A magnetometer may be a three axis magnetometer, which allows the direction of the second well 16 to the casing to be deduced from the three orthogonal components of the magnetic field. A heat shield (not shown) may be provided when a gyro tool is used. Although described above for use in drilling horizontal SAGD well pairs, the methods and apparatuses can be used for other HAGD methods that require precise positioning of one well next to another, for example cross SAGD (X-SAGD), THAI, and VAPEX methods. More than one sensor or component may be carried within the housing 54. The housing 54 may be threaded or otherwise modified so as to allow the coupling of additional lengths of housing 54 that have a similar thread or coupling modification, to increase or decrease the length of chamber 58. The housing 54 may be threaded or otherwise modified so as to allow coupling with a coiled tubing drill string, drill pipe or well bore tractor. The number of supply and return lines do not need to be equal, and include one, two, or a plurality of lines. The coolant does not need to directly contact the components 30, but may indirectly cool the components 30 by passing sufficiently adjacent the components 30. Suitable coolants may be used, including water, nitrogen, propane, hydrocarbons, and other suitable fluids, including gases or liquids. The plates 66 and 68 may centralize the components 30 within chamber 58. The temperature in the chamber 58 may be monitored directly or indirectly and a coolant characteristic such as flow or coolant temperature adjusted in order to maintain the chamber 58 within a predetermined range of temperatures. The actual sensor may be located in the second well, while other related components are located within the first well. One, two, or a plurality of ports may be provided in each ported plate. Each part of tool 94 may be provided in two or more pieces such as plural sleeves connected together.

Referring to FIGS. 1 and 2, further examples of the general concept of the methods and apparatuses disclosed herein will now be described. The general concept is not limited to position sensors or drilling, and may be used in a variety of applications.

For example, a downhole tool 94 is shown in FIG. 2 as having a housing 54, and a sensor 19, such as a position sensor 18 (FIG. 2). Sensor 19 may have components 30 at least partially within the housing 54, for example within chamber 58. The sensor 19 may be provided for monitoring a characteristic of a well 26 (FIG. 1). Tool 94 may also have one or more coolant supply lines 32. Tool 94 may have one or more coolant return lines 34. Lines 32 may extend between a coolant supply 48 (FIG. 1) and the components 30, and lines 34 may extend between the components 30 and a coolant return 52 (FIG. 1).

A coolant loop 97 is shown connected to a downhole supply portion 98 of at least one of the one or more coolant supply lines 32 and to a downhole return portion 99 of at least one of the one or more coolant return lines 34 (FIG. 2). The coolant loop 97, downhole supply portion 98, and downhole return portion 99 may be enclosed within the downhole tool 94.

The downhole tool 94 may be positioned within a previously drilled well, such as well 26, an existing well, a cased well, a completed well, a production well, an injection well (FIG. 1), and other suitable wells. The tubing string connected to housing 54 may not terminate in a drill bit (not shown) in some cases. The sensor 19 (FIG. 2) may be a logging sensor, such as one or more of a bond log sensor, a resurveying logging sensor, gamma ray logging sensor, a spontaneous potential logging sensor, a resistivity logging sensor, a density logging sensor, a sonic logging sensor, a caliper logging sensor, and a nuclear magnetic resonance logging sensor. Some sensors may be one or both of positioned partly outside of chamber 58 (FIGS. 21 and 22, discussed further below), or in fluid contact with the exterior wellbore, for example in the case of a sonic logging sensor (FIG. 20A, discussed further below).

Channels, such as one or more first channels 100 and one or more second channels 102, may be formed in the housing 54 for bypassing coolant past the components 30 and conveying the coolant to pass over the components 30 (FIG. 2). A coiled tubing connector 104 may be present in the housing 54, the coiled tubing connector 104 having ports 60 communicating with the channels 100 and 102 to provide coolant supply and coolant return. Channels 100 may bypass, and channels 102 may convey coolant, in which the channels 100 are connected to the one or more supply lines 32 and channels 102 are connected between channels 100 and the one or more return lines 34. Channels 100 and 102 may house parts of lines 32 and 34, respectively, and may include one or more of ports 60, 61, 63, 65. In other cases coolant may pass over the sensor 19 first, then bypass the sensor 19 on the way uphole. Coolant may be supplied directly over components 30, or indirectly if passed adjacent components 30 or over a component casing (not shown) for protecting components 30 from contact with the coolant.

A characteristic of a well 26 may be monitored using sensor 19 (FIG. 1). Coolant may be supplied through one or more supply lines 32, and returned through one or more return lines 34.

Referring to FIG. 5, the method may involve switching between a first mode and a second mode. In the first mode coolant is supplied through the one or more supply lines 32 and returned through the one or more return lines 34 as described above. In the second mode, coolant is supplied through the one or more supply lines 32 and the one or more return lines 34 and returned up the coiled tubing 40, for example up the coiled tubing annulus 44. Modes may be switched by reconfiguring the tool, for example while the tool is within or out of the well 26. In an example of reconfiguration while the tool 94 is in the well 26, plates 78 may have ports (not shown) that are open to the coiled tubing annulus 44, so that in the first mode some coolant pools in annulus 44, while the bulk of coolant is returned up return line 34. Annulus 44 may be plugged at a suitable point, for example at a point above ground, so that coolant preferentially flows up return lines 34. However, if more coolant is needed to be supplied to the tool 94, annulus 44 is unplugged and connected to a coolant return 52, and return line 34 connected to supply coolant. Thus, the flux of coolant to tool 94 may be increased. Other suitable techniques for switching modes may be used.

Referring to FIG. 19, another example of switching modes is illustrated. When in the first mode, coolant is supplied via supply line 32 and returned via return line 34 through check valve 77 in the uphole portion or end 64 of chamber 58. A check valve (not shown) may be provided on ports 65 in plate 85 so that a pressure in the chamber 58 lower than a coiled tubing annulus pressure, for example when line 34 is sucking coolant uphole, will not lead to appreciable coolant transfer through ports 65 into annulus 44. At least a portion of annulus 44 may be pressurized to an extent sufficient to prevent or reduce undesired filling with coolant while in the first mode. To switch into the second mode, the coolant flow through return line 34 is reversed for example above ground, and coolant supplied through return line 34 across check valve 75 through port 63 in the same fashion as provided by supply line 32, with coolant then passing through ports 61 in plate 83 into chamber 58. Check valve 77 now prevents re-entry of coolant in chamber 58 into return line 34, and coolant is returned up annulus 44 (or an additional return line (not shown) as provided. In some of the embodiments disclosed herein the supply of coolant may be through the annulus 44. The supply of coolant may also be into the uphole portion 64 of chamber 58.

Referring to FIG. 12, an exploded view of the embodiment of FIG. 3 is illustrated, with supply and return lines 32 and 34 omitted for clarity. FIGS. 13-18 illustrate cross-sections taken at the marked points along the tool 94 of FIG. 12. Lines 103 drawn perpendicular to the outer profile 106 of tool 94 in FIGS. 14-15, and 17-18 illustrate exemplary axial placement points of threaded holes 105. A transition component 108 is provided with a coiled tubing connector 104 on one end and a seat 110 on the other end for mounting plate 87 of uphole ported plate assembly 82 within seat 110. Ported plate assemblies 82 and 84 may have an inner tubular 91 for one or more wirelines (not shown). One or more sleeves 112, in this case spacer sleeves 112A and 112B are provided for seating and housing ported plate assemblies 82 and 84, respectively. Sleeves 112 may be added or subtracted as is required to ensure that chamber 58 (FIG. 2) has the required length to house the applicable sensor 19. A further sleeve 114 may be provided to seat the downhole end 115 of ported plate assembly 84, and a bull nose cap 116 added to define secondary chamber 76. Components may be secured together using screws, welding, and other suitable methods, and may incorporate gaskets such as rubber or brass gaskets to ensure a fluid tight seal. In some cases rubber should not be used, in addition to other types of material that may melt in the downhole environment.

The tool 94 may be used in downhole environments hotter than ambient temperature, for example above a range of safe operating temperatures of the sensor 19. Materials other than steel or metal may be used to construct part or all of the apparatuses described herein. For example, the sleeves 112 may be constructed of material that allows the enclosed sensor 19 to operate properly.

Referring to FIGS. 20A-C, an embodiment of tool 94 is illustrated with sensor 19 at least partially in fluid contact with the exterior wellbore 120, for example in the case of a sonic logging sensor 19A. Sensor 19 is housed at least partially within tube 91, which has a hole 122 that allows sensor 19 to communicate with wellbore 120 via a passage 124 defined by a radial sheath 126 extended to housing 54 (FIG. 20A). Thus, the housing may have a port (passage 124) that allows coolant to at least partially discharge into the wellbore. Sheath 126 may extend from an annular saddle 127 surrounding tube 91. Sensor 19 may be cooled one or both of indirectly by coolant passing through chamber 58 (FIG. 20A), or directly via one or more supply lines 32A passing through tube 91 and into contact with sensor 19 (FIG. 20B). Coolant from line 32A may exit tool 94 via window passage 124 into wellbore 120 (FIG. 20A), or may return up the tool 94 via one or more return lines (not shown). A cover (not shown) may seal sensor 19 from wellbore 120, for example if the cover is transparent to signals transmitted or received by sensor 19 for further example if the housing 54 is not transparent to such signals.

Referring to FIGS. 21 and 22 and as mentioned above, components of sensor 19 may be positioned at least partially outside chamber 58, for example at least partially outside of housing 54. For example, at least part of sensor 19 may include one or more high temperature resistant components such as a caliper 130 (FIG. 21), or an antenna 134 (FIG. 22) such as a transmitter or receiver antenna in a resistivity tool 136, that may be mounted for example to housing 54.

Referring to FIG. 23, a video camera 138 may be also be mounted on the tool 94, for example in or on the downhole end 140 of the tool, for further example set up to view laterally and/or forwardly, and cooled by the cooling fluid either separately or together with other sensors. The video camera may be located within the chamber 58 or preferably within the secondary chamber 76, with an opening 141 in the housing 54, or within the bull nose cap 116, that may be provided with a transparent cover or lens 142. The video camera may be placed to receive light from the opening either directly or via a light guide 144 such as an optical fiber or mirrors. The cover or lens is provided to allow the video camera to transmit light to the wellbore or receive light from the wellbore, but prevent fluids escaping from the cooling chamber. In other embodiments, the opening 141 may not be covered so as to allow at least a portion of the coolant to discharge through the opening 141. The camera may extend at least partially outside of the opening 141, for example if at least part of camera 138 is located in a transparent sheath (not shown) extending from opening 141. The video camera may be provided with cables or other two way communication means connecting the camera to surface for instantaneous viewing and control and/or may have recording capability. In all embodiments disclosed herein, various communication means may be used such as wireless, fluid pulse and sonic.

In some cases, the method and system may include one or more temperature sensors, for example, provided within or part of sensor 56. The temperature sensor may be connected to control fluid flow through the one or more coolant supply lines based on a temperature sensed by the temperature sensor. For example, the temperature sensor may be connected to send temperature signals to a controller that in response sends signals to increase or decrease coolant flow depending on the sensed temperature within the housing. The temperature sensor may be in the form of a thermostat valve. A thermostat or thermostat valve may open or throttle, automatically or remotely, when the temperature at, in, or near the housing reaches a predetermined temperature. The thermostatically controlled valve may allow fluid to flow out the end of the tool into the well, for example if the thermostat valve is located on window passage 124. The one or more temperature sensors may monitor temperature outside the housing as well, for example in real time. This provides data to control the down hole temperature. If the temperature starts to rise beyond a target temperature, the pump rate and surface cooling rates may be increased, if the down hole is below the target temperature the pump rate may be decreased. This system also ensures the customer is getting value for their investment and may be used to evaluate any down hole failures to the tools the system is cooling.

In some embodiments, the downhole tool 94 may comprise a production pump, for example instead of or in addition to the sensor 56. One or more coolant supply and return lines 32 and 34 may extend to and from, respectively, the production pump. The pump may be positioned at least partially within housing 54. The production pump may be an electric submersible pump. The system may be used throughout the life of a well to cool the production pump. The housing or flask may cover all or a portion of the pump and the cooling lines and the surface equipment may be permanently installed. One surface installation (pumps, coolant reservoir, cooling tower or heat exchangers) may feed coolant to multiple pumps in multiple wells. The temperature monitoring system may include surface display and recording instruments, down hole thermo couples and a conductor or telemetry system used to communicate between the down hole thermocouples and the surface equipment.

Referring to FIG. 24, another embodiment of a downhole tool 94 and method of use is illustrated. A downhole tool 94 includes a housing 54 enclosing at least a part of a tool component, for example sensor 56. Tool 94 also includes one or more coolant return lines 34, in this case an annulus of the tool 94. At least a portion of lines 34 extend to the housing 54, in order to receive return coolant from housing 54 for example from housing return line 164. Tool 94 also includes one or more coolant supply lines 32. Lines 32 include at least a first portion 160 and a second portion 162. The first portion 160, for example the remainder of the one supply line shown downhole of point 163, is extended to the housing 54 to supply coolant to the housing. The second portion 162 is extended, at a point 163 uphole of the housing 54, to the one or more coolant return lines 34. Thus, a portion of coolant can be supplied to the housing 54, while a portion can be diverted back up the hole without passing through housing 54. The capacity of coolant that can be supplied to the housing 54 (first portion) may be limited by various factors such as the dimensions of the interior of the housing, and the size of ports to the housing. As the coolant travels downhole it may be heated by the formation. To reduce the temperature increase of the first portion of fluid, the second portion of coolant is sent downhole with the first portion for example along direction lines 166 to absorb formation heat and thermally shield the first portion. In the example shown, the use of ports 162 allows a % of coolant, for example 90% to pass along lines 170 through ports 162 back up the hole while only 5% enters the housing 54 along direction line 168. The flux of fluid entering the housing 54 is dictated by the number and size of ports 162 in the example shown. In other cases the first portion and second portion may be carried in respective fluid lines. One or more of the ports 162 may be controlled for example selectively opened or closed on the fly to adjust the proportion of total coolant flow that is passing through ports 162.

In the claims, the word “comprising” is used in its inclusive sense and does not exclude other elements being present. The indefinite articles “a” and “an” before a claim feature do not exclude more than one of the feature being present. Each one of the individual features described here may be used in one or more embodiments and is not, by virtue only of being described here, to be construed as essential to all embodiments as defined by the claims. 

1. A downhole tool comprising: a housing enclosing at least a part of a sensor; one or more coolant supply lines extending to the housing; one or more coolant return lines extending to the housing; one or more first channels, formed in the housing and connected to one of one or more coolant supply lines or one or more coolant return lines, for bypassing coolant past the at least a part of the sensor; and one or more second channels, formed in the housing and connected between the one or more first channels and the other of the one or more coolant supply lines and the one or more coolant return lines in the housing, for conveying the coolant to pass over the at least a part of the sensor; in which the one or more coolant supply lines and the one or more coolant return lines are positioned within coiled tubing.
 2. A downhole tool, comprising: a housing having a coiled tubing connector and defining a chamber terminating in an uphole direction by a ported plate; a sensor having components within the chamber, the sensor being for monitoring a characteristic of a well; and one or more coolant supply lines connected to the chamber.
 3. The downhole tool of claim 2 in which the one or more coolant supply lines are connected to the ported plate.
 4. The downhole tool of claim 2 further comprising one or more coolant return lines connected to the ported plate. 5-9. (canceled)
 10. A downhole tool comprising: a housing having a chamber defined by a downhole ported plate and an uphole ported plate in the housing; a sensor having components within the chamber; and one or more coolant supply lines extending between a coolant supply, located above ground in use, and one of the downhole ported plate or the uphole ported plate.
 11. The downhole tool of claim 10 further comprising one or more coolant return lines extending between a coolant return located above ground in use and the other of the downhole ported plate or the uphole ported plate. 12-29. (canceled)
 30. A position sensor comprising: a housing; a sensor having components within the housing, the sensor being for monitoring in use the location of a second well during drilling of the second well while the housing is in a first well; one or more coolant supply lines extending to the components; and one or more coolant return lines extending to the components.
 31. The position sensor of claim 30 in which the components are within a chamber defined by the housing and connected to receive coolant from the one or more coolant supply lines through one or more ports in a downhole portion of the chamber.
 32. The position sensor of claim 31 in which the downhole portion and an uphole portion of the chamber are each defined by a respective ported plate mounted within the housing.
 33. The position sensor of claim 32 in which the components are mounted to one or both of the ported plate that defines the downhole portion of the chamber and the ported plate that defines the uphole portion of the chamber.
 34. The position sensor of claim 30 in which the components are located within coiled tubing in one of a pair of horizontal wells used for heat assisted gravity drainage.
 35. The position sensor of claim 34 in which the coiled tubing is coil in coil tubing.
 36. The position sensor of claim 30 in which the components comprise a magnetometer.
 37. The position sensor of claim 30 in which monitoring the location of the second well comprises monitoring the location of a drill string. 38-75. (canceled)
 76. A downhole tool, comprising: a production pump; one or more coolant supply lines extending to the production pump; and one or more coolant return lines extending from the production pump.
 77. The downhole tool of claim 1 further comprising a temperature sensor connected to control fluid flow through the one or more coolant supply lines based on a temperature sensed by the temperature sensor.
 78. The downhole tool of claim 77 in which the temperature sensor comprises a thermostat valve.
 79. (canceled) 